1. Field of the Invention
The present invention relates to a steering system for a vehicle. Particularly, the present invention relates to a steering system in which each steerable wheel has a respective electric motor associated with it to effect turning of the steerable wheel independently of turning of any other steerable wheel.
2. Description of the Prior Art
Vehicle steering systems in which each steerable wheel of a vehicle has a respective electric motor associated with it to effect turning of the steerable wheel independently of any other steerable wheel are known. One such steering system is disclosed in U.S. Pat. No. 4,741,409. The steering system disclosed in U.S. Pat. No. 4,741,409 includes a steering gear having a housing which is connectable with the vehicle. First and second rack members are supported for axial movement by the housing and for telescoping movement relative to one another. Each rack member is connected through a pivot joint of a respective tie rod with an associated steerable wheel. A pair of rotatable pinion gears are also supported by the housing. Each pinion gear meshingly engages with a respective one of the rack members. Each pinion gear is connected with a respective one of a pair of electric motors. Energization of one of the electric motors causes rotation of the associated pinion gear which, in turn, moves the associated rack member axially to steer the steerable wheel independently of the other vehicle wheel. The rack members mechanically interconnect when a relative travel limit is reached to block relative telescoping movement between the rack members in the event of a failure of one of the electric motors.
Such a steering gear has the disadvantage of being relatively large and thus occupying a relatively large amount of space within the vehicle. It will be apparent that it is desirable to decrease the size of the steering gear to increase the amount of available space within the vehicle especially when the steering gear is mounted in the engine compartment of the vehicle.